The general purpose of this proposal is to develop refractory strains of the Aedes (St.) scutellaris group of mosquitoes to infection with filarial parasites. Two approaches will be used to achieve this objective: 1) Refractory lines will be isolate from highly susceptible species of Aedes (St.) polynesiensis and Ae. pseudoscutellaris by the genetic method of selection. 2) Through introgressive hybridization, refractory genes of Aedes (St.) malayensis will be incorporated into the genome of Aedes (St.) tabu and possible into Ae. pseudoscutellaris. The developed refractory strains will be used as one of the basic components in establishing the mode of inheritance of susceptibility and refractoriness to infection with filarial parasites in the Ae. scutellaris complex of mosquitoes. Such refractory strains and a knowledge of the mode of inheritance of susceptibility and refractoriness in these mosquitoes may lead to an innovative method of control of human filariasis, based on changing of natural populations of susceptible vectors to refractory ones.